Measuring myocardial physiologic parameters

ABSTRACT

A method for measuring a myocardial physiologic parameter according to an embodiment includes placing an at least partially convex portion of a spectral sensor against an intercostal space of a human over a heart of the human and measuring the physiologic parameter of a myocardium of the heart with the spectral sensor over time during an emergency medical event. The spectral sensor may be configured to determine and visually display a suggested position adjustment for directing the spectral radiation more directly toward the tissue of interest (e.g. the myocardium), and/or for placing the operative elements of the spectral sensor closer to the tissue of interest (e.g. the myocardium).

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.16/369,604, filed Mar. 29, 2019, which is a continuation of U.S. patentapplication Ser. No. 14/926,473, filed Oct. 29, 2015, which itselfclaims the benefit of U.S. Provisional Patent Application Ser. No.62/072,319, filed on Oct. 29, 2014, which is incorporated herein byreference in its entirety for all purposes.

TECHNICAL FIELD

Embodiments of the present invention relate generally to spectralsensors for measuring physiologic parameters, and more specifically tospectral sensors for measuring myocardial physiologic parameters throughan intercostal space.

BACKGROUND

Spectral sensors for noninvasive measurement or calculation ofphysiologic parameters (PP) such as, for example, oxygen saturation,oxygen tension, pH, hematocrit, hemoglobin concentration, anaerobicthreshold, water content, and oxygen consumption, which are described inthe art, for example in U.S. Patent Application Publication No.2011/0205535, published Aug. 25, 2011 (“the '535 Publication”), thecontents of which are incorporated by reference herein in their entiretyfor all purposes. One such spectral sensor 10 is illustrated in FIGS. 1and 2 , reproduced from the '535 Publication, which show a spectraldetector 12, two short-distance radiation sources 14 a, 14 b, and sixlong-distance radiation sources 16 a-16 e. The housing 11 includes aconcave inner surface that is configured for placement against apatient's skin above tissue, for example peripheral muscle tissue, whichis to be monitored. The housing 11 further includes a handle 15 on eachside, as well as apertures 17 a, 17 b for communications interface. Asshown in FIG. 2 , the radiation sources 14 a, 14 b and 16 a-16 e may bepart of a circuit board 18.

However, spectral sensors such as sensor 10 often rely in general ontheir initial positioning over a larger muscle, for example a shoulderor arm muscle, without any indication or assistance in positioning basedupon effectiveness of tissue illumination.

SUMMARY

In Example 1, a system for non-invasively measuring a physiologic statusof a myocardium of a patient according to an embodiment of the presentinvention includes a probe having a housing, wherein the housing isshaped to conform to a general shape of an indentation of an intercostalspace of the patient; an optical spectroscope, at least partiallydisposed within the housing, the optical spectroscope comprising atleast one light source capable of emitting light at a range ofwavelengths, a wavelength-sensitive sensor capable of detecting lightintensity, at two or more distinct wavelengths, of light scatteredand/or reflected by tissue of the myocardium; and a processorcommunicably coupled to a memory, the memory including instructionsthat, when executed by the processor, cause the processor to (1) receivelight intensity measurements from the optical spectroscope, and (2)determine a first magnitude of effectiveness of the at least one lightsource in illuminating the tissue of the myocardium.

In Example 2, the system of Example 1, wherein the housing has agenerally convex outer profile to facilitate maintaining substantiallycontinuous surface contact between the housing and the intercostal spacewhen the housing is rotated.

In Example 3, the system of Example 1, wherein the first magnitude ofeffectiveness is based on an effectiveness of the at least one lightsource in illuminating the tissue of the myocardium.

In Example 4, the system of Example 1, wherein the memory furtherincludes instructions that, when executed by the processor, cause theprocessor to cause a first indication to be communicated to the user,wherein the first indication indicates the first magnitude ofeffectiveness.

In Example 5, the system of any of Examples 1-4, wherein the firstindication is communicated using at least one of a visual display, anaudio tone, a verbal communication, and a haptic vibration of the probe.

In Example 6, the system of any of Examples 1-5, wherein the memoryfurther includes instructions that, when executed by the processor,cause the processor to determine a second magnitude of effectiveness ofdetermining the physiologic status of the myocardium of the patient, andto cause a second indication to be provided to the user, wherein thesecond indication indicates which of the first and second magnitudes ofeffectiveness is larger.

In Example 7, the system of any of Examples 1-6, wherein the secondindication is communicated using at least one of a visual display, anaudio tone, a verbal communication, and a haptic vibration of the probe.

In Example 8, the system of any of Examples 1-7, wherein the probecontains at least one inertial sensor.

In Example 9, the system of any of Examples 1-8, wherein the memoryfurther includes instructions that, when executed by the processor,cause the processor to calculate positional information associated withthe first magnitude of effectiveness, and to direct the user to anoptimal position using directional commands to the user.

In Example 10, the system of any of Examples 1-9, wherein the memoryfurther includes instructions that, when executed by the processor,cause the processor to evaluate the first magnitude of effectivenessover a range of positions of the probe and to direct the user to theoptimal position within the range of positions using directionalcommands to the user.

In Example 11, the system of any of Examples 1-10, wherein thedirectional commands comprise at least one of a visual display, an audiotone, a verbal communication, and a haptic vibration of the probe.

In Example 12, the system of any of Examples 1-11, wherein the inertialsensor comprises one or both of an accelerometer and a gyroscope.

In Example 13, the system of any of Examples 1-12, wherein the probe isincorporated into a self-adhesive electrode attached to the patient'schest.

In Example 14, the system of any of Examples 1-13, wherein the electrodeis a defibrillation electrode.

In Example 15, the system of any of Examples 1-14, wherein the probecomprises conformable material.

In Example 16, the system of any of Examples 1-15, wherein theconformable material includes silicone.

In Example 17, the system of any of Examples 1-16, wherein the memoryfurther includes instructions that, when executed by the processor,cause the processor to compare a spectra received by thewavelength-sensitive sensor against one or more stored representationsof known spectra to identify a type of underlying tissue, wherein thetype of underlying tissue comprises at least one of bone, fat andmyocardium.

In Example 18, the system of any of Examples 1-17, wherein the memoryfurther includes instructions that, when executed by the processor,cause the processor to estimate the first magnitude of effectivenessbased on the comparison.

In Example 19, the system of any of Examples 1-18, wherein the processoris communicably coupled to an electrocardiogram (ECG) sensor configuredto generate an ECG trace associated with the patient; the memory furtherincludes instructions that, when executed by the processor, cause theprocessor to calculate a cross-correlation coefficient between the ECGtrace and the received spectra; and the first magnitude of effectivenessis based on the cross-correlation coefficient.

In Example 20, the system of any of Examples 1-19, wherein the memoryfurther includes instructions that, when executed by the processor,cause the processor to utilize a spectral fit technique to perform thecomparison.

In Example 21, the system of any of Examples 1-20, wherein the spectralfit technique includes a chi-square fit technique.

In Example 22, a method for measuring a myocardial physiologic parameteraccording to an embodiment of the present invention includes placing aspectral sensor comprising at least one radiation source on a patient'sskin in a first position in an intercostal space above the patient'smyocardium, wherein at least a portion of the spectral sensor has aconvex outer profile for placement against a concave profile of theintercostal space; determining a first magnitude of effectiveness of thespectral sensor in measuring the myocardial physiologic parameter in thefirst position; moving, rotating or rolling the spectral sensor from thefirst position to a second position in the intercostal space;determining a second magnitude of effectiveness of the spectral sensorin measuring the myocardial physiologic parameter in the secondposition; comparing the first magnitude with the second magnitude; andbased on the comparison, visually indicating a direction of positionadjustment of the spectral sensor to achieve more effective measurementof the myocardial physiologic parameter.

In Example 23, the method of any of Examples 1-22, wherein the at leastone radiation source comprises two or more long-distance radiationsources, and one or more short-distance radiation sources; the spectralsensor comprises a spectral detector, wherein at least two of the two ormore long-distance radiation sources and at least one of the one or moreshort-distance radiation sources is located on the spectral sensor atdifferent distances from the spectral detector; and the method furthercomprises selecting a radiation source of the two or more long-distanceradiation sources which most effectively illuminates tissue of themyocardium for determining a physiologic parameter of the tissue of themyocardium.

In Example 24, the method of any of Examples 1-23, wherein the housinghas a convex outer profile.

In Example 25, the method of any of Examples 1-24, wherein the firstmagnitude of effectiveness and the second magnitude of effectiveness isbased on an effectiveness of the at least one radiation source inilluminating the tissue of the myocardium when the spectral sensor is inthe first position and the second position, respectively.

In Example 26, the method of any of Examples 1-25, wherein theintercostal space is the second left intercostal space.

In Example 27, the method of any of Examples 1-26, wherein theintercostal space is the third left intercostal space.

In Example 28, the method of any of Examples 1-27, wherein theintercostal space is the fourth left intercostal space.

In Example 29, the method of any of Examples 1-28, wherein the convexouter profile is at least a portion of a cylinder, and wherein rotatingor rolling the spectral sensor comprises rotating the spectral sensorabout a longitudinal axis of the cylinder while the spectral sensorremains in the intercostal space.

In Example 30, the method of any of Examples 1-29, wherein visuallyindicating the direction of position adjustment comprises visuallyindicating a direction of rotation of the spectral sensor to achievemore direct orientation of the at least one radiation source toward thetissue of the myocardium.

In Example 31, the method of any of Examples 1-30, wherein visuallyindicating the direction of position adjustment comprises visuallyindicating a direction of translation of the spectral sensor to achievea closer proximity of the at least one radiation source to the tissue ofthe myocardium.

In Example 32, the method of any of Examples 1-31, wherein visuallyindicating the direction of position adjustment comprises illuminatingat least one light visible on the spectral sensor when the spectralsensor is placed against the skin in the intercostal space.

In Example 33, the method of any of Examples 1-32, further comprisingproviding haptic feedback to further indicate the direction of positionadjustment.

In Example 34, the method of any of Examples 1-33, further comprisingmeasuring the physiologic parameter of the myocardium.

In Example 35, the method of any of Examples 1-34, further comprisingattaching the spectral sensor to the intercostal space and measuring thephysiologic parameter of the myocardium over time.

In Example 36, the method of any of Examples 1-25, further comprisingmeasuring the physiologic parameter of the myocardium over a firstperiod of time when the spectral sensor is in the first position;calculating a first cross-correlation coefficient between a firstelectrocardiogram (ECG) trace taken during the first period of time andthe measured physiologic parameter when the spectral sensor is in thefirst position, wherein the first magnitude of effectiveness is based onthe first cross-correlation coefficient; measuring the physiologicparameter of the myocardium over a second period of time when thespectral sensor is in the second position; and calculating a secondcross-correlation coefficient between a second ECG trace taken duringthe second period of time and the measured physiologic parameter whenthe spectral sensor is in the second position, wherein the secondmagnitude of effectiveness is based on the second cross-correlationcoefficient.

In Example 27, a spectral sensor for measuring a myocardial physiologicparameter according to an embodiment of the present invention includesat least one radiation source; a spectral detector, a housing shaped forplacement against a concave profile of an intercostal space; a visualindicator; and a processor communicably coupled to the at least oneradiation source, the spectral detector, and the visual indicator,wherein, when the housing is placed against the concave profile of theintercostal space, the processor is configured to evaluate aneffectiveness with which the spectral sensor can determine a physiologicparameter of the underlying myocardial tissue, at various positions ofthe spectral detector with respect to the intercostal space, and whereinthe processor is further configured to, based on the evaluation of theeffectiveness, activate the visual indicator so as to indicate adirection of position adjustment of the spectral sensor to achieve moreeffective determination of the physiologic parameter of the underlyingmyocardial tissue.

In Example 38, the spectral sensor of any of Examples 1-37, wherein theat least one radiation source comprises two or more long-distanceradiation sources and one or more short-distance radiation sources, andwherein at least two of the two or more long-distance radiation sourcesand at least one of the one or more short-distance radiation sources arelocated on the spectral sensor at different distances from the spectraldetector.

In Example 39, the spectral sensor of any of Examples 1-38, wherein thehousing comprises a convex outer profile.

In Example 40, the spectral sensor of any of Examples 1-39, wherein theprocessor is configured to evaluate the effectiveness with which thespectral sensor can determine a physiologic parameter of the underlyingmyocardial tissue based on an effectiveness with which the at least oneradiation source illuminates the underlying myocardial tissue.

In Example 41, the spectral sensor of any of Examples 1-40, wherein theprocessor is further configured to receive an electrocardiogram (ECG)trace from an ECG sensor, and a spectra signal from the spectraldetector; and calculate a cross-correlation coefficient between the ECGtrace and the spectra signal, wherein the effectiveness with which thespectral sensor can determine a physiologic parameter of the underlyingmyocardial tissue is based on the cross-correlation coefficient.

In Example 42, the spectral sensor of any of Examples 1-41, wherein theconvex outer profile is at least a portion of a cylinder.

In Example 43, the spectral sensor of any of Examples 1-42, furthercomprising a first module and a second module, wherein at least one ofthe two or more long-distance radiation sources and the one or moreshort-distance radiation sources is disposed on the first module, andwherein the spectral detector is disposed on the second module.

In Example 44, the spectral sensor of any of Examples 1-43, wherein theprocessor is configured to activate the visual indicator to visuallyindicate a direction of rotation of the spectral sensor to achieve moreeffective determination of the physiologic parameter of the underlyingmyocardial tissue.

In Example 45, the spectral sensor of any of Examples 1-44, wherein theprocessor is configured to activate the visual indicator to visuallyindicate a direction of translation of the spectral sensor to achieve acloser proximity of the at least one radiation source to the tissue ofthe myocardium.

In Example 46, the spectral sensor of any of Examples 1-45, wherein thevisual indicator comprises at least one light visible on the spectralsensor when the spectral sensor is placed against the intercostal space.

In Example 47, the spectral sensor of any of Examples 1-46, furthercomprising providing a haptic feedback device to further indicate thedirection of position adjustment.

In Example 48, a system according to an embodiment of the presentinvention includes an electrode assembly comprising a sternum electrodecoupled to an apex electrode; and a pocket coupled to the sternum andapex electrodes so as to be arranged over an intercostal space over aheart of a patient when the sternum electrode is properly positioned onthe right sternum and the apex electrode is properly positioned on theleft torso, wherein the pocket is sized to receive a spectral sensor formeasuring a physiologic parameter of a myocardium of the heart of thepatient.

In Example 49, the system of any of Examples 1-48, wherein the pocketfurther comprises a window configured for placement against skin of thepatient, wherein the window is sized sufficiently to permit radiation tobe emitted from the spectral sensor toward the myocardium by one or moreradiation sources, and to be received from the myocardium to thespectral sensor by one or more detectors.

In Example 50, a system according to an embodiment of the presentinvention includes an electrode assembly comprising a sternum electrodecoupled to an apex electrode; and a spectral sensor coupled to thesternum and apex electrodes so as to be arranged over an intercostalspace over a heart of a patient when the sternum electrode is properlypositioned on the right sternum and the apex electrode is properlypositioned on the left torso, wherein the spectral sensor is configuredto measure a physiologic parameter of a myocardium of the heart of thepatient.

In Example 51, a method for measuring a myocardial physiologic parameteraccording to an embodiment of the present invention includes placing anat least partially convex portion of a spectral sensor against anintercostal space of a human over a heart of the human and measuring thephysiologic parameter of a myocardium of the heart with the spectralsensor over time during an emergency medical event.

In Example 52, the method of any of Examples 1-51, further comprisingattaching the spectral sensor to the intercostal space with adhesive.

In Example 53, the method of any of Examples 1-52, further comprisingpressing the spectral sensor into the intercostal space.

While multiple embodiments are disclosed, still other embodiments of thepresent invention will become apparent to those skilled in the art fromthe following detailed description, which shows and describesillustrative embodiments of the invention. Accordingly, the drawings anddetailed description are to be regarded as illustrative in nature andnot restrictive.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a prior art spectral sensor.

FIG. 2 illustrates a bottom schematic view of placement of radiationsources and a detector of the prior art spectral sensor of FIG. 1 .

FIG. 3 illustrates a front view of a human thoracic cavity, illustratingintercostal spaces and the human heart.

FIG. 4A illustrates placement of an intercostal spectral probe in thefront view of FIG. 3 , according to embodiments of the presentinvention.

FIG. 4B illustrates placement of two portions of a modular intercostalspectral probe in the front view of FIG. 3 , according to embodiments ofthe present invention.

FIG. 5 illustrates a partial cross-sectional perspective view of theplacement of the intercostal spectral probe of FIG. 4A, according toembodiments of the present invention.

FIG. 6 illustrates a side cross-sectional view of the placement of theintercostal spectral probe of FIGS. 4A and 5 , according to embodimentsof the present invention.

FIG. 7 illustrates a top front perspective view of an intercostalspectral probe, according to embodiments of the present invention.

FIG. 8 illustrates a bottom view of an optical spectroscope housed in asensor probe, according to embodiments of the present invention.

FIG. 9 illustrates a translucent view of an intercostal spectral probe,according to embodiments of the present invention.

FIG. 10 illustrates a front perspective view of a human chestillustrating typical placement of external electrodes fordefibrillator-based cardiac monitoring and defibrillation.

FIG. 11 illustrates a front view of the electrode assembly of FIG. 10with an added intercostal spectral probe or probe accommodation pocket,according to embodiments of the present invention.

FIG. 12 illustrates a patient monitoring and control system including aspectral sensor, according to embodiments of the present invention.

FIG. 13 illustrates a computer system, according to embodiments of thepresent invention.

FIG. 14 depicts a flow chart illustrating a method for measuringmyocardial pH or other physiologic parameter with an intercostalspectral probe, according to embodiments of the present invention.

While the invention is amenable to various modifications and alternativeforms, specific embodiments have been shown by way of example in thedrawings and are described in detail below. The intention, however, isnot to limit the invention to the particular embodiments described. Onthe contrary, the invention is intended to cover all modifications,equivalents, and alternatives falling within the scope of the inventionas defined by the appended claims.

DETAILED DESCRIPTION

FIG. 3 illustrates a front view of a human thoracic cavity 30,illustrating intercostal spaces and the human heart, including the first(1), second (2), third (3), fourth (4), and fifth (5) left and rightintercostal spaces, which are the spaces between the ribs. FIG. 4Aillustrates placement of an intercostal spectral sensor, which may alsobe referred to as an intercostal spectral probe 40, in the second leftintercostal space between ribs 42 and 44, according to embodiments ofthe present invention. According to other embodiments, the intercostalspectral probe/sensor 40 is placed in the third or fourth intercostalspace. As shown in FIGS. 5 and 6 , the tissue 54 between ribs 42 and 44and under the intercostal space, including the user's skin, isrelatively thick, and the myocardium 50 of the heart 52 is underneathtissue layer 54. Also, in many cases, the myocardium 50 is not directlybelow one of the intercostal spaces, but is rather offset superior orinferior of the intercostal space. Thus, existing spectral sensors 10are neither shaped nor configured to measure myocardial physiologicparameters. The probe 40 includes a support structure 40A that providesa housing for the optical spectroscope 41. As shown in FIG. 8 , theoptical spectroscope 41 includes at least one emitter 81-86 and at leastone spectral receiver 80. The spectral receiver 80 may be an integrated,miniaturized spectral bench made up, for example, of a diffractiongrating and a complementary metal-oxide-semiconductor (CMOS) imagesensor. The spectral receiver 80 may also include an optical waveguide(e.g., constructed using a lens and fiber optics) that directs theincident light back to a longer handle (not shown) of the probe 40and/or back to a patient monitor (e.g., patient monitor 154 depicted inFIG. 12 ). The optical spectroscope 41 may transmit the rawspectroscopic data back to the patient monitor 154 for processing anddetermination of a magnitude of effectiveness of the radiation source(e.g., the at least one emitter 81-86) in illuminating the tissue of themyocardium. The spectroscopic data may also be used to determinephysiologic parameters such as, for example, SmO2, pH, hematocrit andCO2. In embodiments, a processor separate from the patient monitor 154may also be housed in the probe 40 and may be configured to perform oneor more of these functions and transmit the results of the functions tothe patient monitor 154.

The transmission of data back and forth between the probe 40 and thepatient monitor 154 can be accomplished using any number of differenttypes of data communication technologies. For example, communication maybe wired (e.g., using a serial and/or parallel cable 40B) and/orwireless and may involve any number of various types of networks. Suchnetworks may be, or include, any number of different types ofcommunication networks such as, for example, a bus network, a shortmessaging service (SMS), a local area network (LAN), a wireless LAN(WLAN), a wide area network (WAN), the Internet, a P2P network,custom-designed communication or messaging protocols, and/or the like.The network may include a combination of multiple networks. Varioustypes of wireless communication may be used and may include, forexample, infrared communication, radio frequency (RF) communication(e.g., radiative and/or inductive), acoustic communication, electriccommunication, and/or the like, and may utilize any number ofcommunication protocols such as, for example, Bluetooth®, IEEE 802.11,and/or the like.

As shown, for example, in FIG. 4B, embodiments may include a modularintercostal spectral probe that includes two or more independent modules40C and 40D. In this manner, one or more modules may be positioned indifferent intercostal spaces, as shown in FIG. 4B. A first module 40Cmay include the at least one emitter 81-86, and a second module 40D mayinclude the at least one spectral receiver 80 (e.g., spectral bench). Inembodiments, the first and second modules 40C and 40D may be configuredto communicate with one another via wired and/or wireless communication.In some embodiments, each of the first and second modules 40C and 40Dmay include visual indicators to aid in positioning, as described infurther detail below. In other embodiments, only one of the first andsecond modules 40C and 40D (or less than all of the modules) may includethe visual indicators. That is, for example, it may be more important toachieve a particular position and/or orientation of the second module40D (containing the receiver) and, accordingly, in some embodiments,only the second module 40D includes visual indicators for positioning.According to various embodiments, the modular probe may include a numberof emitter modules 40C and/or a number of receiver modules 40D, and anyone or more of the modules may be configured to communicate with thepatient monitor 154, as described above.

Noninvasive physiologic parameter measurements of the myocardium 50according to the embodiments of the present invention provideclinicians, for example clinicians in an emergency medical situation,with valuable information about the lining of the heart itself; thisinformation cannot be obtained with the same level of relevance fromperipheral muscle tissues, whose pH tends to drop sooner and faster thanthat of the myocardium 50. Furthermore, skeletal muscle pH variesconsiderably within the human body, so skeletal muscle pH readings arenot always able to be reliably correlated with myocardial pH. Measuringmyocardial pH can be used to track blood flow to the heart. The same istrue for other physiologic parameters like oxygen tension andsaturation. Current practices for measuring blood flow as well as thephysiologic status of the myocardial tissue can be highly invasive andnot at all practical in either the pre-hospital setting or in thehospital setting outside of the thoracic surgery suite orcatheterization laboratory.

The probe 40 may be cylindrical in shape, and/or may include acylindrical or otherwise convex outer surface configured to either restwithin the intercostal space, as shown in FIGS. 5 and 6 . In thismanner, the convex outer surface, for example a cylindrical outersurface, which contains a spectral bench (i.e. two or more spectralradiation sources and at least one spectral detector) may be placedcloser to the myocardium 50 than would be possible with a skin interfacesurface of flat or concave shape, according to embodiments of thepresent invention.

While the probe 40 is shown in FIG. 4 as being placed into the third orfourth left intercostal space because such intercostal space is closestto the ventricular myocardium 50 tissue of interest, another intercostalspace may be used. For instance, the second intercostal space may beused to get an estimate associated with atrial tissue.

FIG. 7 illustrates a top front perspective view of an intercostalspectral probe 40, according to embodiments of the present invention.Probe 40 includes visual indicators that assist a user in positioning(which, as used herein, includes orienting) the probe 40 in theintercostal space so as to more or most effectively enable the probe 40to measure physiologic parameters associated with the myocardium 50. Insome embodiments, the probe 40 can evaluate the effectiveness with whichit can measure the physiologic parameters based on the effectivenesswith which the probe 40 can illuminate the tissue of the underlyingmyocardium 50.

As shown in FIG. 7 , a top T of the probe 40 may include one or morevisual indicators 71-73 and 77-79 visible to a user of the probe 40while the probe 40 is placed in the intercostal space with the top Tfacing upwardly and/or outwardly and/or along a direction that is nothidden against the body. The bottom B of the probe 40 may include aspectrographic bench (not shown in FIG. 7 ), similar to that shown inFIG. 2 or 8 , according to embodiments of the present invention. Suchspectrographic bench may take numerous forms and shapes, and may in someembodiments be convex or at least partially convex so as to beaccommodated in the intercostal space. Any of the probes 40 describedherein may include any or a subset of the hardware, software,characteristics, and/or performance of any of the spectral sensors andrelated functionality described in the '535 Publication, according toembodiments of the present invention. The probe 40 may, in someembodiments, be a cylinder or partial cylinder formed about a centralaxis or axis of rotation A, according to embodiments of the presentinvention.

As described in the '535 Publication, a processor (such as processor 150shown in FIG. 12 ) may be configured to select a suitable long-distancesource of the plurality of long-distance sources (such as, for example,the plurality of long-distance sources 81-85 shown in FIG. 8 ) whichmost effectively illuminates the tissue of interest (for example, themyocardium 50), according to embodiments of the present invention. Inthe same way, the processor 150 may be configured to determine astrength or magnitude of the strongest illumination of the tissue ofinterest, for example the myocardium 50. The processor 150 may beconfigured to determine such a strength or magnitude of the strongestillumination, and/or identify the particular long-distance radiationsource which is responsible for most strongly illuminating the targettissue, at multiple different positions of the probe 40 with respect tothe intercostal space. In some embodiments, by determining the strengthor magnitude of illumination, the processor 150 can evaluate theeffectiveness with which a physiologic parameter associated with thetissue of interest can be determined.

Using these magnitude observations and comparisons, as well as knowninformation about the placement of the long-distance radiation sources81-85 and/or short-distance radiation sources 86 and/or detector 80, theprocessor 150 may calculate a spatial orientation adjustment of theprobe 40 with respect to the target tissue that would result inincreased illumination of the target tissue by one or more of thelong-distance radiation sources 81-85 to permit effective determinationof the physiologic parameters of the tissue.

For example, if the processor 150 notices that the strongestlong-distance illumination magnitude of the myocardial tissue formeasuring physiologic parameters is getting weaker as probe 40 isrotated or rolled, for example about central longitudinal axis A ofprobe 40 along direction 56, the visual indicators 73 and/or 77 mayilluminate or change color or be otherwise activated to visually signalthat the user should rotate or roll the probe 40 in direction 58 inorder to achieve better tissue illumination for measuring physiologicparameters of the myocardium 50, according to embodiments of the presentinvention. If the processor 150 notices that the strongest long-distanceillumination magnitude is getting weaker as probe 40 is rotated orrolled, for example about central longitudinal axis A of probe 40 alongdirection 58, the visual indicators 71 or 79 may illuminate or changecolor or be otherwise activated to visually signal that the user shouldrotate or roll the probe 40 in direction 56 in order to achieve bettertissue illumination for measuring physiologic parameters of themyocardium 50, according to embodiments of the present invention.According to such embodiments, the central visual indicator 72 and/or 78may illuminate to indicate to the user that the rotational position ofthe probe 40 is sufficient for accurate or effective measurement of themyocardial physiologic parameters.

In some embodiments, processor 150 can also be directly or indirectlycoupled with an electrocardiogram (ECG) sensor configured to monitorelectrical activity related to a patient's heart, and to generate an ECGtrace. Processor 150 can monitor the generated ECG trace whilesimultaneously monitoring time-varying spectroscopic data from opticalspectroscope 41, and can calculate a cross-correlation between these twosignals. Since in some examples, observable parameters of the patient'smyocardium is expected to be closely correlated with the patient's ECGtrace, the time-varying spectroscopic data received by opticalspectroscope 41 can also be expected to closely correlate with thepatient's ECG trace when optical spectroscope 41 is properlyilluminating and imaging the patient's myocardium. Therefore, processor150 can calculate a cross-correlation coefficient between (i) thepatient's ECG trace (or a parameter derived from the patient's ECGtrace) and (ii) spectroscopic data from optical spectroscope 41, and usethe cross-correlation coefficient as a measure of how effectively theradiation source (e.g., the at least one emitter 81-86) is illuminatingthe tissue of the myocardium, and/or how effectively the opticalspectroscope 41 can determine a physiologic parameter of the patient'smyocardium. The cross-correlation coefficient can be calculated usingstatistical comparisons as known to a person of skill. Thecross-correlation coefficient can therefore provide a mathematicalindication of the correlation between the ECG data and the spectroscopicdata. If processor 150 detects that the cross-correlation is decreasingas probe 40 is translated or rotated in one direction, the visualindicators can visually signal the user to move probe 40 in the oppositedirection. If processor 150 detects that the cross-correlation isincreasing as probe 40 is translated or rotated in one direction, thevisual indicators can visually signal the user to continue moving probe40 in that direction.

According to some embodiments of the present invention, the visualindicators 71-73 and 77-79 are lateral position indicators. In someembodiments, one set of lateral position indicators 71-73 are located onthe top T of the probe 40, and are used to inform the user whether totranslate the entire probe 40 (e.g. without rotation about axis A). Forexample, if probe 40 should be moved along either directionperpendicular to arrow 75, one of visual indicators 71, 73 may beactivated to indicate the direction of lateral translation that has beendetermined to improve an illumination of the desired tissue by thelong-distance radiation source or sources. The middle visual indicator72 may be configured for activation when the processor 150 determinedthat the lateral position (e.g. translation) is as desired, or within acertain range thereof.

According to some embodiments, the probe 40 includes two lateralposition indicators, one being set 71-73, the other being set 77-79.These lateral position indicators function similarly to those describedabove, except they are configured to indicate rotation about an verticalaxis that is perpendicular to axis A. In other words, each set indicateslateral position information with respect to each particular end ofsensor with which it is associated. If visual indicators 71 and 77 areactivated, a clockwise rotation (viewed from above) is indicated; ifvisual indicators 73 and 79 are activated, a counterclockwise rotation(viewed from above) is indicated. If visual indicator 72 is activatedalong with visual indicator 77, this may indicate that the user is toleave the end of probe 40 at which indicator 72 is located stationary,while moving the end at which visual indicator 77 is located in thelateral direction indicated, according to embodiments of the presentinvention.

An inertial sensor system, such as the Analog Devices ADIS164362Tri-Axis Gyroscope Accelerometer, may be used. These inertial sensorsmay be used to map both the rotational position of the probe 40, as wellas its longitudinal position along the intercostal space.

Probe 40 may further include longitudinal translation indicators 74, 76,which visually indicate repositioning of the probe 40 along thedirections indicated by arrow 75, according to embodiments of thepresent invention. For example, arrow 74 may be illuminated or its colorchanged or otherwise activated to indicate translation of the entireprobe 40 along direction 75, for example, along axis A, while arrow 76may be illuminated or its color changed or otherwise activated toindicate translation of the entire probe 40 along the opposite directionindicated by arrow 75.

Visual indicators 71-74 and 76-79 may take various forms, shapes, andarrangements, and one of ordinary skill in the art, based on the presentdisclosure, will appreciate that numerous other visual indicators may beused to achieve the described functionality. The visual indicators maybe lights, including for example light emitting diodes (LEDs). Differentcolors, and/or flashing patterns, and/or brightnesses may be employed.Further, audio and/or haptic feedback devices may be included, either inaddition to or instead of visual indicators, to provide positioningand/or placement feedback. Additional visual or other indicators mayalso be used to alert the user that the probe 40 is correctly placed andmeasuring myocardial physiologic parameters, so that the user may thensecure the probe 40 in its current orientation and placement, forexample with adhesive and/or a strap. This strap may be a strap thatwraps around the chest of the patient and applies a slight or strongdownward force of the probe 40 into the intercostal space, to improveillumination of the myocardial tissue, according to embodiments of thepresent invention. In this manner, the strap or other device that may beused to maintain the position of the probe 40 may also preventenvironmental light (or at least a portion thereof) from interferingwith the operation of the probe 40.

The long-distance radiation sources 81-85 shown in FIG. 8 may eachinclude LEDs (separate LEDs are shown in columns 87, 88, and 89 for eachradiation source 81-85). In some cases, the LEDs of each source 81-85produce a relatively broad bandwidth incident radiation for illuminatingthe myocardium tissue. In other cases, each LED of each column 87, 88,89 emits radiation at a different wavelength and/or wavelength profile,and the positional adjustment features described above may be used toposition the probe 40 such that the most preferred wavelength bestilluminates the target tissue, according to embodiments of the presentinvention.

Because the intercostal tissue 54 is thicker (and thus provides morescattering of applied light radiation) and the myocardium 50 deeper thanthe tissues that would normally be illuminated for physiologic parametermeasurement by sensors such as sensor 10, in some embodiments the LEDsof one or more of the radiation sources 81-85 may be replaced withhigher intensity light sources, for example lasers of tunablewavelength, which permit greater depth penetration of illuminatingradiation, according to embodiments of the present invention. Accordingto some embodiments of the present invention, the radiation fromradiation sources 81-85 may be used by the detector 80 and processor 150to differentiate between muscle and bone.

FIG. 9 illustrates a translucent view of an intercostal spectral probe90, according to embodiments of the present invention. Probe 90 isflexible, and includes a circuit board or platform 91 including aspectrographic bench (examples of which are described above) configuredto face toward the patient (e.g. along arrow 96). The platform 91 may bereinforced by one or more rods 92 which are relatively rigid to preventtorsional distortion of the spectrographic bench upon deformation of theprobe 90. For example, the platform 91 may be rotatable about alongitudinal axis, and the probe 90 may be bent or flexed in the mannershown by line 94, and an internal gyroscope 95 may be configured topermit the spectrographic bench to face downwardly along arrow 96throughout such bending or deformation, according to embodiments of thepresent invention. According to some embodiments, the body of the probe90 is made of a polymer material that may be semi-conformable and/orsemi-rigid, for example with a durometer of 20 on the A Scale.

FIG. 10 illustrates a front perspective view of a human chestillustrating typical placement of external electrodes fordefibrillator-based cardiac monitoring and defibrillation, while FIG. 11illustrates a front view of the electrode assembly of FIG. 10 with anadded intercostal spectral sensor 1108 or sensor accommodation pocket1108, according to embodiments of the present invention. According tosome embodiments, the electrode system 1100 of FIGS. 10 and 11 issimilar to that shown and described in U.S. Patent ApplicationPublication No. 2014/0135666, published on May 15, 2014 (“the '666Publication”), which is incorporated herein by reference in its entiretyfor all purposes.

For example, the electrode system 1100 includes a sternum electrode1102, an apex electrode 1104, a sternal bridge 1106, and a chestcompression monitor 1112, according to embodiments of the presentinvention. A communications cable 1110 communicably couples theelectrodes 1102, 1104, and the chest compression monitor 1112 with anadditional processor or information system, according to embodiments ofthe present invention. Also connected, for example mechanically,physically, and/or communicably with some or all of the other componentsof the system 1100, is a sensor 1108. Sensor 1108 may be a spectralprobe 40 as described above, for example. According to otherembodiments, element 1108 is a pocket for receiving a probe 40. Thepositioning of sensor 1108 or pocket 1108 with respect to the system1100 is such that the probe 40 is placed directly over or into therelevant intercostal space of the patient when the other elements ofsystem 1100 are also properly positioned, according to embodiments ofthe present invention. If element 1108 is a pocket, then the pocket 1108may include a window or transparent material or cutout that permitsoptical interface of the spectrographic bench of a probe 40 with theunderlying intercostal space of the patient.

In embodiments, the probe 40 and/or pocket 1108 may be configured to beadjustable. That is, for example, the position of the probe 40 withrespect to the system 1100 may be able to be changed by a practitioner.In embodiments, the probe 40 may be removably coupled to the system1100, slideably coupled to the system 1100, and/or the like. The pocket1108 may be adjustable such as by being removably coupled to the system1100, slideably coupled to the system 1100, and/or the like. Forexample, in an embodiment, the pocket 1108 may include a first portionof a hook-and-loop fastening material (e.g., Velcro®) and the secondportion or portions of the hook-and-loop fastening material, which isconfigured to mate with the first portion, may be disposed at variouslocations on the system 1108 to allow for adjustment of the position ofthe pocket 1108. In other embodiments, the pocket 1108 may be attachedto the system 1108 using a loop or other engaging structure configuredto slideably engage a system of tracks upon which the pocket 1108 canslide. Any number of other mechanisms and techniques may be used toprovide an adjustable attachment of the probe 40 and/or the pocket 1108to the system 1100.

FIG. 12 illustrates a patient monitoring and control system 120including a spectral probe 40, according to embodiments of the presentinvention. A spectral probe 40, which houses an optical spectroscope 41that is capable of emitting light in a specified wavelength range. Thespectra generated from the light scattered and reflected by theunderlying myocardial tissue and then detected by the opticalspectroscope's 41 detector are then used to implement the functions ofe.g., a muscle oxygen saturation sensor 502, a pH sensor 504, a bloodhematocrit sensor 506, and/or a carbon dioxide sensor 508, according toembodiments of the present invention, though many other physiologicparameter measurement functions can also be implemented using opticalspectroscopic information. Spectral probe 40 is communicably coupledwith a patient monitor 154, which may be, for example, a defibrillatoror an automatic external defibrillator, according to embodiments of thepresent invention. Patient monitor 154 may include or otherwise by incommunication with a processor 150, which is configured to or otherwisecapable of executing all or parts of the methods described herein and/ordescribed in the '535 Publication. A database 152 may be used to storeinformation and/or instructions or other software. The patient monitor154 may have its own display module 155 in communication therewith,and/or the system 120 may include a separate display module 156,according to embodiments of the present invention.

Information about the myocardial physiologic parameter as measured, ormeasured over time, by probe 40 may be displayed on the display module155 of the patient monitor 154 and/or the other display module 156, forexample along with other data about a patient to which the probe 40 isapplied, according to embodiments of the present invention. Such data orinformation may also be stored in database 152, for exampleindependently or with other information about the patient or the medicalencounter for which the spectral probe's 40 data is being collected.

The illustrative system 120 shown in FIG. 12 is not intended to suggestany limitation as to the scope of use or functionality of embodiments ofthe present invention. Neither should it be interpreted as having anydependency or requirement related to any single component or combinationof components illustrated therein. Additionally, any one or more of thecomponents depicted in FIG. 12 may be, in embodiments, integrated withvarious ones of the other components depicted therein (and/or componentsnot illustrated), all of which are considered to be within the ambit ofthe present invention. The hardware elements and/or modules shown inFIG. 12 may be included on the same device and/or distributed acrossmultiple devices, and each such hardware element or module shown in FIG.12 may have its elements or functionality spread across multipledevices.

FIG. 13 is an example of a computer or computing device system 200 withwhich embodiments of the present invention may be utilized. For example,defibrillator 154 and/or the display/control system of probe 40 may beor incorporate a computer system 200, according to embodiments of thepresent invention. According to the present example, the computer systemincludes a bus 201, at least one processor 202, at least onecommunication port 203, a main memory 208, a removable storage media205, a read only memory 206, and a mass storage 207.

Processor(s) 202 can be any known processor, or any known microprocessoror processor for a mobile device. Communication port(s) 203 can be anyof an RS-232 port for use with a modem based dialup connection, a copperor fiber 10/100/1000 Ethernet port, or a Bluetooth® or WiFi interface,for example. Communication port(s) 203 may be chosen depending on anetwork such a Local Area Network (LAN), Wide Area Network (WAN), or anynetwork to which the computer system 200 connects. Main memory 208 canbe Random Access Memory (RAM), or any other dynamic storage device(s)commonly known to one of ordinary skill in the art. Read only memory 206can be any static storage device(s) such as Programmable Read OnlyMemory (PROM) chips for storing static information such as instructionsfor processor 202, for example.

Mass storage 207 can be used to store information and instructions. Forexample, flash memory or other storage media may be used, includingremovable or dedicated memory in a mobile or portable device, accordingto embodiments of the present invention. As another example, hard diskssuch as SCSI drives, an optical disc, an array of disks such as RAID, orany other mass storage devices may be used. Bus 201 communicably couplesprocessor(s) 202 with the other memory, storage and communicationblocks. Bus 201 can be a PCI/PCI-X or SCSI based system bus depending onthe storage devices used, for example. Removable storage media 205 canbe any kind of external hard-drives, floppy drives, flash drives, zipdrives, compact disc-read only memory (CD-ROM), compact disc-re-writable(CD-RW), or digital video disk-read only memory (DVD-ROM), for example.The components described above are meant to exemplify some types ofpossibilities. In no way should the aforementioned examples limit thescope of the invention, as they are only exemplary embodiments ofcomputer system 200 and related components.

FIG. 14 depicts a flow chart 1500 illustrating a method for measuring amyocardial physiologic parameter with an intercostal spectral sensor,according to embodiments of the present invention. A method formeasuring a myocardial physiologic parameter includes placing a spectralprobe 40 on a patient's skin in a first position in an intercostal spaceabove the patient's myocardium 50 (block 150), wherein the spectralprobe 40 comprises two or more long-distance radiation sources 81-85,one or more short-distance radiation sources 86, and a spectral detector80, at least two of the two or more long-distance radiation sources81-85 and at least one of the one or more short-distance radiationsources 86 located on the spectral probe 40 at different distances fromthe spectral detector 80, wherein at least a portion of the spectralprobe 40 has a convex outer profile for placement against a concaveprofile of the intercostal space, as illustrated in FIGS. 4-6 . Themethod may further include selecting a radiation source of the two ormore long-distance radiation sources which most effectively illuminatestissue of the myocardium for determining a physiologic parameter of thetissue of the myocardium 50 when the spectral probe 40 is in the firstposition, and determining a first magnitude of effectiveness of theradiation source in illuminating the tissue of the myocardium 50 in thefirst position (block 152).

The method may further include repositioning the spectral probe 40(block 154), for example by rotating or rolling the spectral probe 40from the first position to a second position in the intercostal space,and determining a second magnitude of effectiveness of the radiationsource in illuminating the tissue of the myocardium 50 for determining aphysiologic parameter of the tissue of the myocardium 50 when thespectral probe 40 is in the second position (block 156). The firstmagnitude may be compared with the second magnitude (block 158), and,based on the comparison, the probe 40 may be configured to visuallyindicate a direction of position adjustment of the spectral probe 40 toachieve more effective illumination of the tissue of the myocardium 50for determining a physiologic parameter of the tissue of the myocardium50 by the two or more long-distance radiation sources 81-85 (block 160).

In some embodiments, the convex outer profile of the probe 40 is atleast a portion of a cylinder, and wherein rotating or rolling thespectral probe 40 includes rotating the spectral probe 40 about alongitudinal axis A of the cylinder while the spectral probe 40 remainsin the intercostal space. Visually indicating the direction of positionadjustment may include visually indicating a direction of rotation ofthe spectral probe 40 to achieve more direct orientation of the two ormore long-distance radiation sources 81-85 toward the tissue of themyocardium 50. Visually indicating the direction of position adjustmentmay include visually indicating a direction of translation of thespectral probe 40 to achieve a closer proximity of the two or morelong-distance radiation sources 81-85 to the tissue of the myocardium50. In some cases, visually indicating the direction of positionadjustment comprises illuminating at least one light 71-74, 76-79visible on the spectral probe 40 when the spectral probe 40 is placedagainst the skin in the intercostal space.

A spectral probe 40 for measuring a myocardial physiologic parameteraccording to some embodiments of the invention includes two or morelong-distance radiation sources 81-85, one or more short-distanceradiation sources 86, a spectral detector 80, wherein at least two ofthe two or more long-distance radiation sources 81-85 and at least oneof the one or more short-distance radiation sources 86 are located onthe spectral probe 40 at different distances from the spectral detector80, and wherein at least a portion of the spectral probe 40 has a convexouter profile for placement against a concave profile of an intercostalspace (as illustrated, for example, in FIGS. 4-6 ). Such a probe 40 mayinclude one or more visual indicators, for example 71-74 and 76-79, aswell as a processor (e.g. 150 and/or 202) communicably coupled to thetwo or more long-distance radiation sources 81-85, the one or moreshort-distance radiation sources 86, and the visual indicator 71-74 and76-79, wherein, when the convex outer profile is placed against theconcave profile of the intercostal space, the processor 150, 202 isconfigured to evaluate an effectiveness with which the two or morelong-distance radiation sources 81-85 illuminate underlying myocardialtissue, for purposes of determining a physiologic parameter of theunderlying myocardial tissue, at various positions of the spectral probe40 with respect to the intercostal space, and wherein the processor 150,202 is further configured to, based on the evaluation of theeffectiveness, activate the visual indicator (e.g. one or more of 71-74and 76-79) so as to indicate a direction of position adjustment of thespectral probe 40 to achieve more effective illumination of the tissueof the myocardium 50, for purposes of determining the physiologicparameter of the underlying myocardial tissue.

Such a spectral probe 40 may include a convex outer profile that is atleast a portion of a cylinder. The processor 150 may be configured toactivate the visual indicator (e.g. one or more of 71-74 and 76-79) tovisually indicate a direction of rotation 56, 58, and/or a direction oftranslation 75, of the spectral probe 40 to achieve more effectiveillumination of the tissue of the myocardium 50 or a closer proximity ofthe two or more long-distance radiation sources 81-85 to the tissue ofthe myocardium 50.

A system according to some embodiments of the present invention includesan electrode assembly 1100 including a sternum electrode 1102 coupled toan apex electrode 1104, and a pocket 1108 coupled to the sternum 1102and apex 1104 electrodes so as to be arranged over an intercostal spaceover a heart 52 of a patient when the sternum electrode 1102 is properlypositioned on the right sternum and the apex electrode 1104 is properlypositioned on the left torso (e.g. as shown in FIG. 10 ), wherein thepocket 1108 is sized to receive a spectral probe 40 for measuring aphysiologic parameter of a myocardium 50 of the heart of the patient.

Such a system may further include a window configured for placementagainst skin of the patient, wherein the window is sized sufficiently topermit radiation to be emitted from the spectral probe 40 toward themyocardium 50 by one or more radiation sources, and to be received fromthe myocardium 50 to the spectral probe 40 by one or more detectors 80.

A system according to some embodiments of the present invention includesan electrode assembly 1100 including a sternum electrode 1102 coupled toan apex electrode 1104, and a spectral sensor 1108, which may also bereferred to as spectral probe 40, coupled to the sternum and apexelectrodes 1102, 1104 so as to be arranged over an intercostal spaceover a heart 52 of a patient when the sternum electrode 1102 is properlypositioned on the right sternum and the apex electrode 1104 is properlypositioned on the left torso, wherein the spectral sensor 1108 isconfigured to measure a physiologic parameter of a myocardium 50 of theheart of the patient.

A method for measuring a myocardial physiologic parameter according toan embodiment of the present invention includes placing an at leastpartially convex portion of a spectral probe 40 against an intercostalspace of a human over a heart 52 of the human and measuring aphysiologic parameter of a myocardium 50 of the heart with the spectralprobe 40 over time during an emergency medical event. Such method mayfurther include attaching the spectral sensor to the intercostal spacewith adhesive, and/or pressing the spectral sensor into the intercostalspace, according to embodiments of the present invention.

Various modifications and additions can be made to the exemplaryembodiments discussed without departing from the scope of the presentinvention. For example, while the embodiments described above refer toparticular features, the scope of this invention also includesembodiments having different combinations of features and embodimentsthat do not include all of the described features. Accordingly, thescope of the present invention is intended to embrace all suchalternatives, modifications, and variations as fall within the scope ofthe claims, together with all equivalents thereof.

What is claimed is:
 1. A system for assisting sensor position on apatient, the system comprising: a probe comprising a plurality ofsensors, the plurality of sensors comprising: one or more first sensorsconfigured to generate first sensor data representing one or morephysiologic parameters of a subject, and one or more second sensorsconfigured to generate second sensor data representing a position of theprobe; one or more indicators; and one or more processors communicablycoupled to the plurality of sensors and the one or more indicators,wherein the one or more processors are configured to: while the probe ispositioned at a first position on the subject, determine, based on thefirst sensor data, a first metric representing an effectiveness of theprobe in determining the one or more physiologic parameters of thesubject at the first position, while the probe is positioned at a secondposition on the subject, determine, based on the first sensor data, asecond metric representing an effectiveness of the probe in determiningthe one or more physiologic parameters of the subject at the secondposition, compare the first metric and the second metric, and indicate,using the one or more indicators, a suggested position adjustment of theprobe to the user based on the comparison and the second sensor data. 2.The system of claim 1, further comprising a patient monitor systemcomprising at least some of the one or more processors, wherein theprobe is configured to be removably coupled to the patient monitorsystem.
 3. The system of claim 1, wherein the first sensor data isindicative of a blood flow of the subject.
 4. The system of claim 1,wherein the one or more first sensors comprise: one or more radiationsources, and one or more spectral detectors.
 5. The system of claim 1,wherein the first sensor data represents at least one of: an SmO2measurement associated with the subject, a pH measurement associatedwith the subject, a hematocrit measurement associated with the subject,or a CO2 measurement associated with the subject.
 6. The system of claim1, wherein the first sensor data comprises: a plurality ofelectrocardiogram (ECG) traces associated with the subject, andspectroscopic data associated with the subject.
 7. The system of claim6, wherein determining the first metric comprises: determining a firstcross-correlation coefficient between (i) a first ECG trace obtainedwhile the probe was positioned at the first position on the subject, and(ii) a first set of the spectroscopic data obtained while the probe waspositioned at the first position on the subject.
 8. The system of claim7, wherein determining the second metric comprises: determining a secondcross-correlation coefficient between (i) a second ECG trace obtainedwhile the probe was positioned at the first position on the subject, and(ii) a second set of the spectroscopic data obtained while the probe waspositioned at the second position on the subject.
 9. The system of claim8, wherein determining the second metric comprises: determining adifference between the second cross-correlation coefficient and thefirst cross-correlation coefficient.
 10. The system of claim 1, whereinthe one or more second sensors comprise at least one inertial sensor.11. The system of claim 1, wherein the one or more second sensorscomprise at least one accelerometer.
 12. The system of claim 1, whereinthe one or more second sensors comprise at least one gyroscope.
 13. Thesystem of claim 1, wherein the first sensor data represents at least oneof: a rotational position of the probe, or a longitudinal position ofthe probe along the subject.
 14. The system of claim 1, whereinindicating the suggested position adjustment of the probe to the usercomprises: indicating a suggested direction of translation for theprobe.
 15. The system of claim 14, wherein indicating the suggesteddirection of translation for the probe comprises: presenting an arrowhaving the suggested direction of translation for the probe.
 16. Thesystem of claim 1, wherein indicating the suggested position adjustmentof the probe to the user comprises: indicating a suggested rotation forthe probe.
 17. The system of claim 16, wherein indicating the suggestedrotation for the probe comprises at least one of: indicating a suggestedclockwise rotation of the probe using a first indicator of the one ormore indicators, or indicating a suggested counterclockwise rotation ofthe probe using a second indicator of the one or more indicatorsdifferent from the first indicator.
 18. The system of claim 1, whereinthe one or more indicators comprise one or more visual indicators. 19.The system of claim 1, wherein the one or more indicators comprise oneor more audio feedback devices.
 20. The system of claim 1, wherein theone or more indicators comprise one or more haptic feedback devices.